System and Method for Plasma Reduced Platelet Collection

ABSTRACT

A method and apparatus for collecting plasma reduced platelets potentially suspended in a synthetic solution from a donor. Whole blood is drawn from the donor and introduced into a separation chamber. Platelets are extracted from the separation chamber into a container, using, for example, surge (with anticoagulated plasma or a synthetic solution) or push methodologies. The remaining blood components in the separation chamber are returned back to the donor. The steps of drawing whole blood and introducing the whole blood into the separation chamber, extracting platelets from the separation chamber into the container, and returning the remaining components in the chamber back to the donor are repeated. The sequestered platelets in the container are reintroduced into the separation chamber, whereupon a plasma reduced platelet product is extracted.

TECHNICAL FIELD

The present invention relates to systems and methods for plateletcollection, and particularly to systems and methods for concentratingand collecting platelets.

BACKGROUND ART

Apheresis is a procedure in which individual blood components can beseparated and collected from whole blood temporarily withdrawn from asubject. Typically, whole blood is withdrawn through a needle insertedinto a vein of the subjects arm and into a cell separator, such as acentrifugal bowl. Once the whole blood is separated into its variouscomponents, one or more of the components can be removed from thecentrifugal bowl. The remaining components can be returned to thesubject along with optional compensation fluid to make up for the volumeof the removed component. The process of drawing and returning continuesuntil the quantity of the desired component has been collected, at whichpoint the process is stopped. A central feature of apheresis systems isthat the processed but unwanted components are returned to the donor.Blood components separated may include, for example, a high densitycomponent such as red blood cells, an intermediate density componentsuch as platelets or white blood cells, and a lower density componentsuch as plasma.

Among various blood component products obtainable through apheresis, thedemand for plasma reduced platelet products is rapidly growing. This isparticularly because, with the improvement in cancer therapy, there is aneed to administrate more and more platelets to patients with loweredhemopoietic function. Platelets are fragments of a large cell located inthe marrow called a megakaryocyte and primarily contribute to hemostasisby performing aggregation function, although they also have a role intissue healing. Normal platelet counts are 150,000-400,000/mm³ in theadult. Platelet counts under 20,000/mm³ can cause various troubles suchas spontaneous bleeding.

Platelets have a short half-life of 4-6 days and the number of donors islimited. Therefore, in producing plasma reduced platelet products, it isimportant to harvest platelets from the whole blood supplied by a donorat a maximum yield and in a required amount. Further, it is known thatthe contamination of plasma reduced platelet product by white bloodcells can lead to serious medial complications, such as GVH reactions.Therefore, it is also very important to keep the level of contaminationby white blood cells as low as possible, while efficiently collectingplatelets. To this end, various techniques have been developed. Forexample, using “surge” technology, after whole blood is collected andconcentrically separated within a centrifuge into higher density,intermediate density and lower density components and plasma isharvested (so-called “draw” step), the plasma is supplied through thecentrifuge at a surge flow rate, that is, a flow rate that increaseswith time. By performing the surge, platelets can be preferentiallydisplaced from the intermediate density components, which exist as abuffy coat mainly comprising a mixture of platelets and white bloodcells, and plasma reduced platelet products can thereby be produced atan increased yield. Instead of using surge technology, the plateletlayer can also be extracted from the centrifuge by means of a layer“push” in which anticoagulated whole blood is introduced into the bowluntil the platelet layer is pushed out, or by using a combination ofsurge and push methodologies. After harvesting a desired component orcomponents, the residual blood components mostly comprising red bloodcells are returned to the donor (so-called “return” step).

Typically, 450-500 ml of whole blood is processed during one cycle whichcomprises the above-mentioned successive steps. This amount is based on15% or less of the total amount of blood in humans and, if more thanthis amount is taken out of the body at once, the donor may suffer fromblood pressure lowering or dizziness. Using surge technology, theconcentration of the sequestered platelet product ranges from 0.8×10⁶/μLto 2.6×10⁶/μL (typically 1.5×10⁶/μL), with moderate leukocyteconcentration. Pushed platelet product concentration tends to be higherbut leads to greater leukocyte and red blood cell residualcontamination.

This resulting platelet concentration is often too low for plateletproduct compatibility with arising pathogen inactivation methods.Additionally, simultaneous plasma collection of one to two additionalplasma units may be prevented due to the relatively high volume ofplasma captured with the platelet product. The relatively high plasmaprotein content in the platelet product is also less desirable in termsof recipient tolerance.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the invention, a method forcollecting plasma reduced platelets from a donor is presented. Wholeblood is drawn from the donor, anticoagulated, and introduced into aseparation chamber. Platelets are extracted from the separation chamberinto a container and the remaining blood components in or out of theseparation chamber are returned back to the donor. The steps of drawingwhole blood and introducing the whole blood into the separation chamber,extracting platelets from the separation chamber into the container, andreturning the remaining components back to the donor are repeated. Aftera desired quantity of platelets is sequestered into the container,platelets from the container are reintroduced into the separationchamber, whereupon a plasma reduced platelet product is extracted.

In accordance with related embodiments of the invention, extractingplatelets and/or the plasma reduced platelet product from the separationchamber may include extracting platelets by surge elutriation or layerpush methodologies or a combination of both. Whole anticoagulated bloodmay be added to the separation chamber prior to reintroducing plateletsfrom the container into the separation chamber, so as to form a cell bedat a periphery of the separation chamber. Additionally or alternatively,whole anticoagulated blood may be added to the separation chamber duringplatelet reintroduction so as to bring platelet layer towards theelutriation radius, or after platelet reintroduction for perfectingplatelet separation and standardizing conditions of initiating plateletextraction. Returning remaining blood components in the separationchamber back to the donor may include returning back to the donor plasmaand/or red blood cells.

In further related embodiments of the invention, the steps of drawingwhole blood and introducing the whole blood into the separation chamber,extracting platelets from the separation chamber into the container,returning the remaining components in the chamber back to the donor maybe repeated until a desired volume of platelets is extracted. In someembodiments, reintroducing the platelets from the container andextracting a plasma reduced platelet product is only done once. However,in other embodiments, the steps may be repeated until a desired volumeor concentration of reduced plasma platelet product is obtained.Additionally or alternatively, plasma may be added to the plasma reducedplatelet product to adjust the plasma reduced platelet product to apre-determined volume or predetermined concentration. This plasma can beadded through the bowl or via a dedicated plasma line.

In accordance with another embodiment of the invention, a system forcollecting plasma reduced platelets from a donor includes means fordrawing whole blood from the donor. A separation chamber separates thewhole blood into a plurality of components, the components including aplatelet component. The platelet component is stored in a container. Thesystem also includes a means for returning at least one of the pluralityof components from the bowl back to the to the donor, and a flow meansfor connecting the means for drawing whole blood, the separationchamber, the container, and the means for returning at least one of theplurality of components. A controller controls the flow means, the meansfor returning, and the separation chamber so as to repeatedly draw wholeblood from the donor into the separation chamber, extract platelets fromthe separation chamber into the container, and return remainingcomponents in the separation chamber back to the donor. After apredetermined volume of platelets has been sequestered in the container,platelets from the container are reintroduced into the separationchamber so as to extract a plasma reduced platelet product from theseparation chamber.

In accordance with yet another embodiment of the invention, a system forcollecting plasma reduced platelets from a donor is presented. Anapheresis system draws whole blood from a donor and separates the wholeblood into a plurality of components including a platelet component anda non-platelet component using a separation chamber. The plateletcomponent is stored into a container while the non-platelet bloodcomponents are returned back to the donor. A controller controls theapheresis system such that upon obtaining a predetermined volume ofplatelets in the container, platelets from the container arereintroduced into the separation chamber so as to extract a plasmareduced platelet product from the separation chamber.

In accordance with another embodiment, a method for plasma reduced bloodcomponent collection during blood processing is presented. The methoddraws blood from a subject through a venous-access device and into ablood component separation device until a predetermined amount ofwithdrawn blood is in the blood component separation device. The drawnblood is then centrifuged within the blood component separation devicesuch that the withdrawn blood is separated into at least a first bloodcomponent and a second blood component. The method then removes thefirst blood component from the blood component separation device using asurge elutriation method such that the first blood component istransferred to a first component storage container. The method thenreturns the second blood component to the subject through thevenous-access device. The draw and return steps may be repeated one ormore times until an appropriate amount of first blood component isremoved.

The method then partially fills the blood component separation devicewith whole blood and reintroduces the removed first blood component intothe blood component separation device. Reintroducing the first bloodcomponent creates an enlarged layer of the first blood component withinthe blood component separation device. The enlarged layer of first bloodcomponent can be removed from the blood component separation deviceusing a surge elutriation method such that the enlarged layer of firstblood component is transferred to the first blood component storagecontainer. The remaining blood components, including the second bloodcomponent can be returned to the subject through the venous-accessdevice.

In some embodiments, centrifuging the blood further separates the bloodinto a third blood component in addition to the first blood componentand the second blood component. The first blood component may beplatelets, the second blood component may be red blood cells, and thethird blood component may be plasma. Additionally, the surge elutriationmethod may include reintroducing removed plasma (e.g., the third bloodcomponent) into the blood component separation device at an increasingrate until the first blood component (e.g., the platelets) is removedfrom the blood component separation device. Returning the second bloodcomponent to the subject may also include returning the plasmareintroduced into the blood component separation device (during thesurge process) to the subject.

In still other embodiments, a system for plasma reduced blood componentcollection during blood processing comprising is presented. The systemmay include a venous access device for drawing a first volume of wholeblood from a subject and returning blood components to the subject. Thesystem may also include a blood component separation device, a returnline, and a reintroduction line. The blood component separation deviceseparates the drawn blood into a first blood component and a secondblood component. The blood component separation device may also beconfigured to send the first blood component to a first blood componentbag using a surge elutriation method. The return line fluidly connectsthe venous-access device and the blood component separation device andis used to return the second blood component to the subject. Thereintroduction line fluidly connects the first blood component bag andthe blood component separation device, and is used to reintroduce thefirst blood component into the blood component separation device when asecond volume of whole blood is withdrawn from the subject.Reintroducing the first blood component creates an enlarged layer of thefirst blood component within the blood component separation device. Theenlarged layer of first blood component may be removed from the bloodcomponent separation device using a surge elutriation method.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the invention will be more readily understoodby reference to the following detailed description, taken with referenceto the accompanying drawings, in which:

FIG. 1 is a schematic diagram of an apheresis machine, in accordancewith one embodiment of the invention;

FIG. 2 is a schematic diagram of a disposable system for use with themachine of FIG. 1, in accordance with one embodiment of the invention;

FIG. 3 is a side view of a centrifuge bowl for use with the machine ofFIG. 1, in accordance with one embodiment of the invention;

FIG. 4 is a flow chart depicting a method for collecting plasma reducedplatelets from a donor, in accordance with one embodiment of theinvention; and

FIG. 5 is a schematic diagram of a three-line apheresis machine, inaccordance with additional embodiments of the invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring to FIGS. 1 and 2, an apheresis apparatus 10 uses a bloodcomponent separation device, such as a standard Latham type centrifuge11 for separating anticoagulated whole blood into its constituentcomponents, as described in U.S. Pat. No. 3,145,713, which is herebyincorporated by reference. Other types of separation chambers anddevices may be used, such as, without limitation, an integralblow-molded centrifuge bowl, as described in U.S. Pat. Nos. 4,983,156and 4,943,273, which are hereby incorporated by reference. Thecentrifuge 11 includes a rotating bowl 12 and stationary input andoutput ports PT1 and PT2 that are typically closely coupled to the bowlinterior by a rotary seal 74 (see FIG. 3). The input port PT1 of thecentrifuge 11 is in fluid communication with a venous access devices 24(e.g., a phlebotomy needle) via a blood filter F1, a tube 28 and aY-connector 30 when a valve V1 is open. The venous access device 24 maybe replaced with a whole blood bag (not shown) in case the whole bloodis to be first pooled and then supplied. The tube 28 has compatibilitywith blood, as is all the tubing in the apparatus 10. The outlet portPT2 of the centrifuge 11 is selectively coupled by a tube 36, a valve V2and a tube 37 with a first container 18 labeled plasma suspended from aweight scale 33. A second container 20 labeled platelets is selectivelycoupled via the tube 36, a valve V3 and a tube 39 to the outlet portPT2. Additionally, a third container 22 labeled plasma reduced platelets(CP) is selectively coupled via the tube 36, a valve V4 and a tube 35 tothe outlet port PT2. Both second container 20 and third container 22 mayalso be suspended by weight scales 67 and 77, respectively.

A bag or container 16 for storing an anticoagulant is in fluidcommunication with the venous access device/phlebotomy needle 24 via abacteria filter F2, a tube 32 and the Y-connector 30. The bacteriafilter F2 prevents any bacteria in the anticoagulant (ACD) container 16from entering the system. Containers 16, 18, 20, and 22 are preferablyplastic bags made of a blood compatible material. Peristaltic pumps P1,P2 and P3, together with the valves V1, V2, V3, and V4 control thedirection and duration of flow through the apparatus 10 in response tosignals generated by a line sensor 14, a donor pressure monitor (DPM)M1, a system pressure monitor (SPM) M2 and air detectors D1, D2 and D3.The air detectors D1, D2 and D3 detect the absence or presence of fluid.The pressure monitors M1 and M2 monitor pressure levels within theapparatus 10. The line sensor 14 is an optical sensor and detects thepresence of blood components passing through the line sensor 14 from theoutput port PT2.

In initial operation, the pumps P1 and P3 are energized to prime thetube 28 of the apparatus 10 with the anticoagulant from the container16. The anticoagulant passes through the filter F2 and Y-connector 30before reaching the air detector D1. The air detector D1 senses thepresence of the anticoagulant at D1 and terminates the anticoagulantpriming operation. During the priming operation, the valve V2 is openand sterile air displaced from bowl 12 by the anticoagulant enters thetop port PT3 of the air/plasma container 18. The venous access device 24is then inserted into the donor and the draw step is ready to becommenced.

FIG. 4 is a flowchart depicting a method for collecting blood components(e.g., platelets) from a subject, in accordance with one embodiment ofthe invention. During draw step 401, whole blood is drawn from thesubject, typically at a rate of about 80 ml/min. and mixed with theanticoagulant using the pumps P1 and P3 (referring back to FIGS. 1-3).The pump P3 mixes the anticoagulant from the container 16 with the wholeblood drawn from the subject or a bag in which it is pooled. The valveV1 is open, allowing the anticoagulated whole blood to pass through thetube 28 and blood filter F1 before being pumped into the separationdevice 12 through the inlet port PT1.

The whole blood is introduced into the bottom of the separation device12 through a feed tube (not shown), step 202 of FIG. 4. The ratio of theanticoagulant to whole blood is typically about 1:10. The operation ofeach of the pumps and valves in the apheresis apparatus 10 can beperformed in accordance with desired protocols under the control of acontroller (not shown), which may be, for example, a microprocessor.

Referring to FIG. 3, the centrifuge 11 has the fixed inlet port PT1 andthe fixed outlet port PT2. The rotary seal 74 fluidly couples thestationary inlet port PT1 to the lower interior portion of the bowl 12,and the outlet port PT2 to an upper portion of the bowl interior forcollecting separated fractions. A core 72 occupies a volume coaxial withthe interior of bowl 12 and provides a separation region between thewall of the core 72 and the outer bowl wall 70.

As the bowl 12 is rotated, centrifugal forces separate theanticoagulated whole blood admitted into the bottom of the bowl into redblood cells (RBC), white blood cells (WBC), platelets and plasma. Thenumber of rotations of the bowl 12 can be selected, for example, withina range of 4,000 to 6,000 rpm, and is typically 4,800 rpm. The blood isseparated into different fractions in accordance with the componentdensities. The higher density component, i.e., RBC 60, is forced to theouter wall 70 of the bowl 12 while the lower density plasma 66 liesnearer the core 72. A buffy coat 61 is formed between the plasma 66 andthe RBC 60. The buffy coat 61 is made up of an inner layer of platelets64, a transitional layer 68 of platelets and WBC and an outer layer ofWBC 62. The plasma 66 is the component closest to the outlet port fromthe separation region and is the first fluid component displaced fromthe bowl 12 via the outlet port PT2 as additional anticoagulated wholeblood enters the bowl 12 through the inlet port PT1.

Returning to FIG. 1, the displaced plasma passes through the line sensor14, the tube 36, a 3-way T-connector 26, and the valve V2 (in the openposition) and enters the first container 18. The plasma entering thefirst container 18 is drawn from the container 18 by the pump P2 viatube 42, valve 5 (in the open position), Y-connector 92 and tube 40 fromthe lower port PT4 and is recirculated into the bowl 12 through theinlet port PT1 via Y-connector 91 and line 41. The recirculated plasmadilutes the anticoagulated whole blood entering the bowl 12 and allowsthe blood components to separate more readily. An optical sensor 21 isapplied to a shoulder portion of the bowl 12 for monitoring each layerof the blood components as they gradually and coaxially advance towardthe core 72 from the outer wall 70 of the bowl 12. The optical sensor 21may be mounted in a position at which it can detect the buffy coatreaching a particular radius, and the steps of drawing the whole bloodfrom the donor 401 and introducing the whole blood into the bowl 402 maybe terminated in response to the detection.

The amount of whole blood processed by the bowl 12 may be varied inresponse to at least one characteristic associated with the whole blood,such as the hematocrit value, the number of platelets, the total amountof blood or the like of the whole blood, as described in copending U.S.patent application Ser. No. 09/392,880, filed Sep. 9, 1999, entitledApheresis Apparatus and Method for Producing Blood Products, which ishereby incorporated by reference. This variable control can beimplemented under the control of a microcomputer, as aforementioned.Alternatively, each of them can be implemented manually.

The platelets are extracted from the bowl into a container, step 403 ofFIG. 4. In extracting the platelets from the bowl, various methodologiesmay be employed, including, without limitation, dwell, surge, and/orpush methodologies. For illustrative purposes, platelet extraction basedon a dwell and surge technique will now be described in detail.

After the whole blood has been introduced into the centrifuge 11, step402 of FIG. 4, the valve V1 is closed and the pump P1 is stopped so thatblood is no longer drawn from the donor, and dwell is commenced. Duringthe dwell, the pump P2 recirculates plasma 66 through the bowl 12 at amoderate rate (for example, about 100 ml/min. in FIG. 4) for about 20 to30 seconds. At this flow rate, the buffy coat 61 is diluted by theplasma and widens but the platelets do not leave the bowl 12. Thedilution of the buffy coat allows the heavier white blood cells tosediment to the outer side of the buffy coat, resulting in a betterseparation between the lighter platelets layer 64 and the heavier whiteblood cells layer 62. As a result, the transitional layer 68 is reduced.The dwell period also allows the flow patterns in the bowl 12 tostabilize and allows more time for microbubbles to leave the bowl 12 andbe purged.

After dwell, the surge step is commenced. In the surge, the speed of thepump P2 is increased in 5-10 ml/min. increments to recirculate plasmauntil reaching a platelet surge velocity of about 200-250 ml/min. Theplatelet surge velocity is the velocity at which platelets can leave thebowl 12 but not red blood cells or white blood cells. The plasma exitingthe bowl becomes cloudy with platelets and this cloudiness is detectedby the line sensor 14. The line sensor 14 consists of an LED which emitslight through blood components leaving the bowl 12 and a photo detectorwhich receives the light after it passes through the components. Theamount of light received by the photo detector is correlated to thedensity of the fluid passing through the line.

When platelets first start leaving the bowl 12, the line sensor outputstarts to decrease. The valve V3 is opened and the valve V2 is closedand the platelets are collected in container 20. Once the majority ofthe platelets are removed from the bowl 12, the fluid exiting the bowlbecomes less cloudy. This lessening of cloudiness is detected by theline sensor 14, whereupon valve V3 is closed.

After the platelets have been collected, return step 404 (see FIG. 4) isinitiated. During return step 404, the rotation of the bowl 12 isstopped and the remaining blood components in the bowl 12 are returnedto the donor by reversal of rotation of the pump P1 via the venousaccess device 24 with the valve V1 open. The valve V2 is also opened toallow air to enter the centrifuge bowl during the return. The plasmafrom the container 18 dilutes the remaining blood components in the bowl12. Namely, the pump P2 mixes the plasma with the returning componentsin the bowl 12 with the valve V2 open, diluting the returning red bloodcells component with plasma to speed up the return time. When theremaining blood components in the bowl have been returned to the donor,the return step 404 is terminated.

Referring to FIG. 4, the steps of drawing whole blood from the donor,step 401, introducing the whole blood into a separation chamber, step402, extracting platelets from the separation chamber into a container,step 403, and returning the remaining components back to the donor, step404, are repeated until a desired volume of platelets is sequestered inthe container 20, step 405. Typically, steps 401-404 are repeated two tofour times, with about 450-500 ml of whole blood processed per cycle.The sequestered platelet concentration is typically about 1.5×10⁶/μL.

The platelets in container 20 are then re-introduced into the bowl 12,step 406 of FIG. 4, forming a layer of platelets that is several timeslarger than that obtained by processing only one cycle of wholeanticoagulated blood. For example, in some embodiments, the plateletlayer volume is approximately equal to the average volume of one cyclemultiplied by the number of platelet sequestering cycles plus one. Theplatelets are drawn from port PT5 of container 20 by pump P2 via tube43, valve 7 (in the open position) Y-connector 92, and tube 40, andinput into bowl 12 through the inlet port PT1 via Y-connector 91 andline 41. To minimize contact between the platelets and bowl 12, the bowl12 may be partly filled with anticoagulated whole blood drawn from thedonor 401 prior to re-introduction of the platelets. The whole bloodforms a cell bed at the periphery of the bowl 12 that serves as a bufferbetween the periphery of the bowl and the platelets, reducing plateletclumping. Additionally or alternatively, whole anticoagulated blood maybe added to the separation chamber during platelet reintroduction so asto bring platelet layer towards the elutriation radius, or afterplatelet reintroduction for perfecting platelet separation andstandardizing conditions of initiating platelet extraction.

Using, for example, surge or push methodologies, a plasma reducedplatelet concentration is extracted from the layer of platelets that nowreside in bowl 12, step 407 of FIG. 4. The plasma reduced plateletproduct is sequestered in container 22 via line sensor 14, tube 36,3-way T-connector 26 and valve V4 (in the open position). Plateletproduct concentration is typically in the range of 2.6×10⁶/μL to5.2×10⁶/μL, which is 2-3 times that of platelets sequestered whenprocessing only one cycle of whole anticoagulated blood.

It should be noted that the surge elutriation technique may use avariety of fluids other than plasma to extract either the platelets orthe reduced plasma platelet product from the separation chamber (e.g.,saline solution may be used). Additionally, the platelets that arereintroduced into the separation chamber may be re-anticoagulated toprevent the platelets from coagulating and/or clumping. For example, theplatelet collection bag 20 or the reduced plasma platelet product bag 22may be pre-loaded with a quantity of anticoagulant so that the plateletsand/or reduced plasma platelet product mix with the anticoagulant asthey are drawn from the separation chamber. Additionally oralternatively, sufficient anticoagulant may be added as the whole bloodis withdrawn from the subject such that enough anticoagulant is stillpresent in the platelets prior to re-processing. In either scenario, theamount of anticoagulant added the whole blood and/or extracted plateletsmust be weighed against the safety of the subject. In particular, theamount of anticoagulant should be limited so as to prevent a largequantity of anticoagulant being returned to the subject.

It should also be noted that once the platelets and the reduced plasmaplatelet product are collected, a platelet preservative solution may beadded to help preserve and store the platelets for later use. Thepreservative solution can be added to the platelets and platelet productafter collection (e.g., from a separate bag or storage container), orthe platelet collection bag 20 and the reduced plasma platelet productbag 22 may be pre-loaded with the additive solution.

If additional reduced plasma platelet product is required, each of thesteps 401-407 may now be repeated until a desired quantity of plasmareduced platelet product is collected. In various embodiments, plasmamay be added to the plasma reduced platelet product so as to adjust theplasma reduced product to a predetermined volume or concentration.

As shown in FIG. 5, embodiments of the apheresis apparatus can bethree-line systems 500 having, in addition to some or all of thecomponents discussed above with regard to the two line system 10, adedicated return line 27 and a dedicated draw line 29. In suchembodiments, both the return line 27 and the draw line 29 may have adedicated pump that controls the flow and pressure within the lines. Forexample, the return line 27 may have a dedicated return pump P5 and thedraw line may have a dedicated draw pump P4. In addition to thededicated pumps, each line may also include a pressure sensor (e.g.,pressure sensor M1 on the return line and pressure sensor M2 on the drawline) that allow the system 500 to monitor the pressure within the linesand adjust the flow rate based on the pressure measurements.

Additionally, as mentioned above, platelet additive solution may beadded to the collected and stored platelets. To facilitate this process,the two-line system 10 and/or the three-line system 500 may include aplatelet additive storage container 510 and a platelet additive line 520that may be fluidly connected to tube 40 at point 530. In a similarmanner to the other lines and tubes within the system, the plateletadditive line 520 may also include a valve V7 that prevents/allows flowthrough the platelet additive line 520. Such embodiments may also have aline 540 fluidly connecting the platelet collection bag 20 and thereduced plasma platelet product bag 22. This line may include a valve V4and a filter 550, such as a leukoreduction filter.

The described embodiments of the invention are intended to be merelyexemplary and numerous variations and modifications will be apparent tothose skilled in the art. All such variations and modifications areintended to be within the scope of the present invention.

1. A method for collecting plasma reduced platelets from a donor, themethod comprising: a) drawing whole blood from the donor; b) introducinganticoagulant into the whole blood drawn from the donor c) introducingthe anticoagulated whole blood into a separation chamber, wherein theseparation chamber separated the anticoagulated blood into a number ofblood components; d) extracting plasma from the separation chamber intoa plasma container e) extracting platelets from the separation chamberinto a platelet container; f) returning at least part of the remainingblood components in the separation chamber and plasma container back tothe donor; g) repeat steps a and d; h) reintroducing platelets from thecontainer into the separation chamber; and i) extracting a volume of aplasma reduced platelet product from the separation chamber.
 2. Themethod according to claim 1, wherein extracting platelets from theseparation chamber includes extracting the platelets by surgeelutriation.
 3. The method according to claim 2, wherein extractingplatelets from the separation chamber by surge includes surging with atleast one of anticoagulated plasma or synthetic solution, wherein thesynthetic solution is selected from a group consisting of saline andplatelet additive solution.
 4. The method according to claim 1, whereinextracting platelets from the separation chamber includes extracting theplatelets by layer push.
 5. The method according to claim 1, whereinextracting the plasma reduced platelet product from the separationchamber includes extracting the plasma reduced platelets by surgeelutriation.
 6. The method according to claim 5, wherein extracting theplasma reduced platelet product from the separation chamber includessurging with at least one of anticoagulated plasma or a syntheticsolution, wherein the synthetic solution is selected from a groupconsisting of saline and platelet additive solution.
 7. The methodaccording to claim 1, wherein extracting the plasma reduced plateletproduct from the separation chamber includes extracting the plasmareduced platelets by layer push.
 8. The method according to claim 1,further comprising adding additional anticoagulant to the plateletswithin the container prior to reintroducing the platelets into theseparation chamber.
 9. The method according to claim 1, whereinreturning remaining blood components includes returning blood componentsin the separation chamber and in the plasma container.
 10. The methodaccording to claim 1, wherein returning remaining blood components inthe separation chamber back to the donor includes returning red bloodcells.
 11. The method according to claim 1, further comprising repeatingsteps a-f at least once.
 12. The method according to claim 1, furthercomprising adding at least one of anticoagulated plasma or syntheticsolution to the plasma reduced platelet product.
 13. The methodaccording to claim 12, wherein adding at least one of anticoagulatedplasma or synthetic solution includes adding a calculated volume ofplasma or synthetic solution so as to adjust the plasma reduced plateletproduct to a predetermined volume or predetermined concentration. 14.The method according to claim 1, further comprising repeating steps a-i.15. The method according to claim 14, further comprising adding at leastone of plasma or synthetic solution to the plasma reduced plateletproduct.
 16. The method according to claim 15, wherein adding at leastone of plasma or synthetic solution includes adding a calculated volumeof plasma so as to adjust the plasma reduced platelet product to apredetermined volume.
 17. A system for collecting plasma reducedplatelets from a donor, the system comprising: a) means for drawingwhole blood from the donor there through; b) means for introducinganticoagulant into the whole drawn blood c) a separation chamber forseparating the anticoagulated whole blood into a plurality ofcomponents, the components included a platelet component, d) a containerfor storing the anticoagulated plasma component e) a container forstoring the platelet component; f) means for returning at least one ofthe plurality of components from the bowl back to the to the donor; g) aflow means for connecting the means for drawing whole blood, theseparation chamber, the container, and the means for returning at leastone of the plurality of components; and h) a controller for controllingthe flow mean, means for returning, and the separation chamber so as torepeatedly draw whole blood from the donor into the separation chamber,extract platelets from the separation chamber into the container, andreturn remaining components in the separation chamber back to the donor,wherein after a predetermined volume of platelets has been sequesteredin the container, platelets from the container are reintroduced into theseparation chamber so as to extract a plasma reduced platelet productfrom the separation chamber.
 18. The system according to claim 17,wherein the separation chamber separates platelets from the whole bloodby elutriation with at least one of anticoagulated plasma or syntheticsolution.
 19. The system according to claim 17, wherein the separationchamber separates platelets from the whole blood by layer push.
 20. Asystem for collecting plasma reduced platelets from a donor, the systemcomprising: a) an apheresis system for drawing whole blood from a donor,separating the whole blood into a plurality of components including aplatelet component and a non-platelet component using a separationchamber, and storing the platelet component into a container while thenon-platelet blood components are returned back to the donor; and b) acontroller for controlling the apheresis system such that upon obtaininga predetermined volume of platelets in the container, platelets from thecontainer are reintroduced into the separation chamber so as to extracta plasma reduced platelet product from the separation chamber.
 21. Thesystem according to claim 20, wherein the separation chamber separatesplatelets from the whole blood by elutriation with at least one ofanticoagulated plasma or synthetic solution.
 22. The system according toclaim 20, wherein the separation chamber separates platelets from thewhole blood by layer push.
 23. A method for plasma reduced bloodcomponent collection during blood processing comprising: (a) drawingblood from a subject through venous-access device and into a bloodcomponent separation device until a predetermined amount of withdrawnblood is in the blood component separation device (b) centrifuging thewithdrawn blood within the blood component separation device such thatthe withdrawn blood is separated into at least a first blood componentand a second blood component; (c) removing the first blood componentfrom the blood component separation device using a surge elutriationmethod such that the first blood component is transferred to a firstcomponent storage container; (d) returning the second blood component tothe subject through the venous-access device; (e) repeating steps (a)through (d); (f) partially filling the blood component separation devicewith whole blood; (g) reintroducing the removed first blood componentinto the blood component separation device, thereby creating an enlargedlayer of the first blood component within the blood component separationdevice; (h) removing the enlarged layer of first blood component fromthe blood component separation device using a surge elutriation methodsuch that the first blood component is transferred to the first bloodcomponent storage container; and (i) returning the second bloodcomponent to the subject through the venous-access device.
 24. A methodaccording to claim 23, wherein the blood processing device is acentrifuge bowl.
 25. A method according to claim 23, wherein the firstblood component is platelets and the second blood component is red bloodcells.
 26. A method according to claim 23, wherein centrifuging theblood further separates the blood into a third blood component inaddition to the first blood component and the second blood component.27. A method according to claim 26, wherein the third blood component isplasma.
 28. A method according to claim 27, wherein the plasma isremoved from the blood component separation device and stored in aplasma storage container.
 29. A method according to claim 28, whereinthe surge elutriation method includes reintroducing the removed plasmainto the blood component separation device at an increasing rate untilthe first blood component is removed from the blood component separationdevice.
 30. A method according to claim 29, wherein returning the secondblood component to the subject also includes returning the plasmareintroduced into the blood component separation device to the subject.31. A method according to claim 23, further including introducinganticoagulant into the withdrawn blood.
 32. A method according to claim23, wherein steps (a) through (d) are repeated until a desired amount offirst blood component is collected.
 33. A method according to claim 23,further including repeating steps (a) through (i) until a desired amountof first blood component is collected.
 34. A method according to claim23 wherein the first blood component removed from the enlarged layer isplasma reduced.
 35. A system for plasma reduced blood componentcollection during blood processing comprising: a venous access devicefor drawing a first volume of whole blood from a subject and returningblood components to the subject; a blood component separation device forseparating the drawn blood into a first blood component and a secondblood component, the blood component separation device configured tosend the first blood component to a first blood component bag using asurge elutriation method; a return line fluidly connecting thevenous-access device and the blood component separation device forreturning the second blood component to the subject; a reintroductionline fluidly connecting the first blood component bag and the bloodcomponent separation device, wherein the first blood component withinthe first blood component bag is reintroduced into the blood componentseparation device when a second volume of whole blood is withdrawn fromthe subject, thereby creating an enlarged layer of the first bloodcomponent within the blood component separation device, the enlargedlayer of first blood component being removed from the blood componentseparation device using a surge elutriation method.
 36. A systemaccording to claim 35, wherein the blood processing device is acentrifuge bowl.
 37. A system according to claim 35, wherein the firstblood component is platelets and the second blood component is red bloodcells.
 38. A system according to claim 35, wherein the blood componentseparation device further separates the whole blood into a third bloodcomponent in addition to the first blood component and the second bloodcomponent.
 39. A system according to claim 38, wherein the third bloodcomponent is plasma.
 40. A system according to claim 38, wherein theplasma is removed from the blood component separation device and storedin a plasma storage container.
 41. A system according to claim 40,wherein the surge elutriation method includes reintroducing the removedplasma into the blood component separation device at an increasing rateuntil the first blood component is removed from the blood componentseparation device.
 42. A system according to claim 38, wherein the bloodcomponent separation device also returns the third blood component tothe subject in addition to the second blood component.
 43. A systemaccording to claim 35 further including an anticoagulant line connectedto an anticoagulant source, the anticoagulant line introducinganticoagulant into the drawn blood.
 44. A system according to claim 35,wherein the first blood component from the first and second draw volumesare reintroduced into the blood component separation device when a thirdvolume of whole blood is withdrawn from the subject, thereby creating asecond enlarged layer of the first blood component within the bloodcomponent separation device, the second enlarged layer of first bloodcomponent being removed from the blood component separation device usinga surge elutriation method.